Renaming index.html to index.shtml

[Jel]

I have a bunch of pages in directories that are the default index.html but want to change them to index.shtml so I can use virtual includes. Is this likely to cause problems with SES in regards to both the indexed pages and backlinks?

They are the indexes of each directory on my LL and as far as I am aware no-one uses domain/dir/index.html when linking to my categories, just the domain/dir/ so I am wildly guessing there shouldn't be too much of a problem, but an educated guess tells me I will run into problems if I just blindly go and rename each index .shtml - how can I make these changes without fucking evrything up, if it is at all possible to change in the first instance.

Many thanks in advance